This invention relates to a vertical engine for driving an implement such as walk behind lawn mower and more particularly to an improved lubricating system and component layout for such an engine.
A wide variety of implements are driven by small displacement internal combustion engines that are normally mounted on the implement in such a way that the output shaft of the engine rotates about a generally vertically extending axis. The walk behind type of lawn mower is a typical example of an implement that is driven by an engine disposed in such an orientation. Of course, the engine is provided with a lubricating system which includes a lubricate reservoir that is formed within the crankcase chamber of the engine. In order to reduce the emissions of unwanted gases to the atmosphere, it has been the practice to provide even such small engines with closed crankcase venilating systems. With such systems, the blow by gases of the crankcase are returned to the chamber of the engine for further combustion by a crankcase ventilating system that recycles these crankcase gases back to the engine induction system normally through the air cleaner of the engine.
Although the engine is normally operated with its crankshaft rotating about a vertically extending axis, it is quite common with certain types of implements such as the walk behind lawn mower, for the operator to stop the engine and turn the implement onto its side for servicing such as to remove grass which may have clogged the outlet of the lawn mower. When the engine is turned on its side, the lubricant can flow into the induction systems through the crankcase ventilation system. This has a number of disadvantages. In the first instance, there may be developed hydraulic lock in the cylinder that can make starting difficult and can, in fact, damage the engine. Alternatively, the lubricant may be depleted from the crankcase sufficiently so that the engine is not adequately lubricated on restarting. In any event, this flow of lubricant back into the induction can be messy at best.
It is, therefore, a principal object to this invention to provide an improved lubricating and crankcase ventilating system for a small engine that is designed to drive an implement that can be tilted to its side for servicing.
It is a further object of this invention to provide an improved lubricating and crankcase ventilating system for an engine which will preclude the flow of lubricant from the crankcase into the engine induction system regardless of the disposition of the engine.
It is another object of this invention to provide an improved lubricating and crankcase ventilating systm for an engine that will preclude the flow of lubricant into the engine induction system when the engine is being serviced.
With engines having crankcase ventilating systems of the type described, it is desirable, if not essential, to provide a system wherein lubricant can be separated from the crankcase gases and returned to the crankcase. The recycled crankcase gases will contain large amounts of lubricant due to the fact that the lubricant exists to a large extent in a vapor state within the crankcase during the engine running. Therefore, it is a common practice to provide some form of lubricant separator within the crankcase ventilation system that returns the lubricant to the crankcase. However, such lubricant separators also present the problem that they may in fact cause lubricant to flow from the crankcase to the induction system when the engine is shifted to a non-normal condition during servicing of the associated implement.
It is, therefore, a still further object of this invention to provide a lubricant recovery system for a crankcase ventilating system of an engine that will preclude against the flow lubricant into the engine induction system when the engine is disposed in a non-normal position.
In connection with the formation of the crankcase ventilation system and the oil return from that system back to the crankcase, it is normally the practice to form at least a portion of the conduits from separate pipes that must be assembled into the engine. The use of such separate piping not only adds to the cost of the engine but also introduces the possibilities that the piping may interfere with the components of the engine, such as the crankshaft, which rotate within the crankcase.
It is, therefore, a still further object of this invention to provide an improved and simplified conduit system for the crankcase ventilation system of an internal combustion engine.
It is yet another object of this invention to provide an oil return conduit for a crankcase ventilating system that is formed within a wall of the engine and hence which will not interfere with the running components of the engine nor will it require the use of separate pipes.
As should be readily apparent that engines of the type which have been discussed should be very simple so as to maintain low cost and easy serviceability. However, it is also essential that the engine provide a relatively good output in relation to its displacement so as to permit the use of small engines for driving the implements. However, it is also important that all of the components be adequately lubricated. In order to achieve the aforenoted effects, it has been the normal practice to employ some form of splash type lubricating system for this type of engine. In that the engine is disposed with its output shaft rotating about a vertically disposed axis, it is desirable that the camshaft of the engine also be rotatably journaled about a parallel, vertically disposed axis. Such an orientation permits simplicity in the driving arrangement for the camshaft. However, the vertical orientation makes it difficult to insure that the camshaft is adequately lubricated by splash systems.
It is, therefore, a still further object of this invention to provide an improved splash type of lubricating system for an engine having vertically disposed crankshafts and camshafts.
It is a further object of this invention to provide an improved simplified oil slinger arrangement for lubricating the upper bearing of a vertically disposed camshaft for an engine of this general type.
In connection with engines of the type which have been previously discussed, it is also essential that the auxiliaries for the engines such as the carburetor, air cleaner and muffler be disposed in such a way that the engine will be compact and yet these devices can serve their intended functions. Furthermore, it is essential that the components be laid out in such a way that they do not interfere with the cooling of the engine and, in fact, that these components receive the necessary amount of cooling air themselves.
It is, therefore, a still further object of this invention to provide an improved component layout for an internal combustion engine for powering implements.
It is yet another object of this invention to provide an improved component arrangement and cooling system for an engine of this type.